Re: [PATCH v2 4/8] scripts: add glimpse.sh for indexing the kernel

[Julia Lawall]

On Fri, 17 Jun 2016, Luis R. Rodriguez wrote:

> On Fri, Jun 17, 2016 at 11:44:26AM +0200, Julia Lawall wrote:
> > I'm not sure that this is worth it.  It adds a dependency on a tool that
> > seems not to be well maintained.  In terms of Coccinelle, I'm not sure
> > that it gives a big benefit.
> >
> > Attached is a graph showing the file selection time for Coccinelle for a
> > selection of fairly complex semantic patches.  Coccigrep is just a
> > line-by-line regexp search implemented in ocaml, gitgrep uses git grep.
> > In most cases, glimpse is clearly faster.
> >
> > On the other hand, it seems that glimpse often selects more files.
> > Sometimes a few more, eg 16 vs 14, and sometimes quite a lot more, eg 538
> > vs 236.  I suspect that this is because glimpse considers _ to be a space,
> > and thus it can have many false positives.  There are, however, a few
> > cases where glimpse also selects fewer files.
> >
> > The file processing time (ie parsing the file, searching for, matches of
> > the semantic patch in the file, and performing the transformation) is
> > normally much higher than the file selection time.
> >
> > So it seems that git grep is currently a better option for the kernel.
>
> Great, thanks, consider this patch dropped, do we want the heuristics
> for the cache index in place though or should I drop that as well ?

I assume you mean this patch:

[PATCH v2 3/8] coccicheck: add indexing enhancement options

I think it should be dropped.  It adds complexity and git grep works
pretty well.  If people want to use something else, they can use SPARGS,
or a .cocciconfig file, eg:

[spatch]
options = --use-glimpse

julia